1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device, and also relates to a method of manufacturing the same.
2. Description of the Related Art
In general, metal wiring in a semiconductor integrated circuit device is made of aluminum (Al) or an aluminum alloy containing a small amount of silicon (Si) or copper (Cu).
For forming the Al or Al alloy wiring, an Al or Al alloy film is superposed on a substrate which is formed with semiconductor circuit elements. Subsequently, a photoresist film is coated on the Al or Al alloy film and then formed with a wiring pattern by photolithography. The Al or Al alloy wiring is formed by etching the Al or Al alloy film using the wiring pattern as a mask.
In the course of photolithography, when reflectance of the Al or Al alloy film is high relative to light which is used for exposure of the photoresist film superposed on the Al or Al alloy film, a problem is raised that the exposure can not provide a fine wiring pattern on the photoresist film due to halation.
For antihalation, it has been available to superpose on the Al or Al alloy film a TiN film having a lower reflectance to the exposure light as compared with the Al or Al alloy film (see "Proceeding 10th, VMIC(1993), page 248, FIG. 1(d)"). For this purpose, the TiN film, which is formed by normal reactive DC sputtering and has a stoichiometric composition where Ti (titanium) and N (nitrogen) are in the ratio 1:1 in number of atoms, has been used (see "Thin Solid Films, 97(1982), page 73, FIGS. 5 and 6").
Hereinafter, "ratio" will be defined as the "ratio in number of atoms" throughout the specification.
Although the TiN film made of Ti and N in the ratio 1:1 has a lower reflectance than the Al or Al alloy film, a film made of a metal material having an even lower reflectance makes it possible to provide a further finer wiring pattern on the photoresist film.
Further, although the sputtering is normally used to form the TiN film, a film forming speed is low for the TiN film having the ratio 1:1 (see "Thin Solid Films, 153(1987), page 292, FIG. 2(a)"). This leads to reduction in throughput, and thus is disadvantageous in view of mass productivity.